The present invention broadly relates to a drive assembly. In particular, the present invention relates to a motor pump assembly for slip-controlled brake systems, that includes a device for transforming rotary movements into translatory movements.
Drive assemblies comprising a device for transforming rotatory motions into translatory motions, for instance oscillating motions, find a wide variety of fields of application in general mechanical engineering. In particular, in industrial hydraulics, motor vehicle hydraulics and in process engineering, drive systems of such drive assemblies are widely used. The kinematics of the assemblies are durably controllable with high precision even under very different conditions of use.
An example of a motor pump assembly is found in the German patent application having the official filing number P 40 278 48.4, which discloses a pump assembly, actuated by means of an electric drive assembly that supplies pressure fluid to a slip-controlled motor vehicle brake system. The drive shaft of the electric motor has, at the shaft end, an eccentric pin. Two pump pistons of a radial piston pump bear against the eccentric pin through the intermediary of a needle bearing. When the drive shaft, guided in rolling bearings, is turned, the pin which is eccentrically arranged at the shaft end performs an eccentric curve which results in the oscillating movement of the pump pistons.
Current designs, such as that described above, permit a limited variation in the delivery volume of pressure fluid by means of a speed control of the electric motor, for example. This result is due to the piston stroke which is determined by the eccentric curve. Typically required control engineering measures demand an improvement over currently-used designs.